Transmitter for sound recording and reproducing machines.



S. I. PRESCOTT TRANSMITTER FOR SOUND RECORDING AND REPBODUCING MACHINES.

APPLIOATION FILED In. 18, 1909.

965,326. Patented July 26, 1910.

PCT VEST \NVENTOR M 7 m: MORRIS PETERS co. WASHINGTON, D c.

UNITED STATES PATENT ()FFICE.

SYDNEY I. PRESCOTT, OF CAMDEN, NEW JERSEY.

TRANSMITTER FOR SOUND RECORDING AND REPRODUCING MACHINES.

To all whom it may concern:

Be it known that I, SYDNEY I. Pnnsoor'r, a citizen of the United States, residing at Camden, county of Camden, in. the State of New Jersey, have invented a new and use ful Transmitter for Sound Recording and Reproducing Machines, of which the fol.- lowing is a specification.

This invention relates to a transmitter for sound recording and reproducing machines.

Heretofore, hollow sound conductors have been used which varied widely in form. Certain types of these conductors were tubular and of even diameter. In certain other types the diameter of the tube varied. In the latter type, one end of the conductor wa larger than the other, so that sound, in passing therethrough from the smaller end toward the larger, would be amplified. In both types the sound wave in passing through the tube is deformed, the deformation depending upon the material of which the tube is constructed, its shape, and upon the fact that the soundavaves are deflected from the walls of the conductor and forced to meet on the axial line of the same, thereby producing crashes of sound. Furthermore, sound conductors heretofore used, the wall of which was formed of vibratory material, produced a secondary set of soundwaves in the air surrounding the conductor. These secondary sound-waves were never the .same as the soundwaves passing through the conductor, for the reason that the frequency of vibration of the conductor wall was not the same as the frequency of the air vibration within the conductor, and that in consequence the frequency of the secondary sound-waves was the resultant of the combined forces and unlike either. The presence of secondary sound-waves is objectionable for they detract from the purity of the initial sound.

here it is necessary to conduct a soundwave from one point to another it is desirable that the wave at the delivery pointbe not deformed. Furthermore, in certain instances where sound recording and reproducing machines are used, it is highly desirable to concentrate the sound at a predetermined point without deformation of the wave.

It is one of the objects of this invent-ion, therefore, to provide a hollow conductor for sound recording and reproducing ma- Specification of Letters Patent.

Application filed March 18, 1909.

Patented July 26, 1910.

Serial No. 484,281.

chines, the purpose of which is to concentrate the sound-waves passing theretlnough at a predetermined point.

A further object is to provide means for producing concentration at a predetermined point of sound-waves passing through a conductor in their initial purity.

A further object is to provide a sound conductor backed by sound-absorbing material so that no secondary sound-waves are produced in the air surrounding the con ductor.

Still another object is to provide means for conducting sound-waves from one point to another without producing sound crashes which. detract from the purity of the sound.

With these and other objects not specifically mentioned, in view, the invention consists in certain constructions which will be hereinafter fully described and then specifically pointed out in the claims hereunto appended.

In the drawings which form a part of this specification and in which like characters of reference indicate the same parts, Figure 1 is a longitudinal section of a device constructed in accordance with the invention, and Fig. 2 is a cross sectional view 'of the device illustrated in Fig. 1.

In carrying the invention into effect, there is provided a hollow conductor, the wall of which is shaped to cause concentration of sound-waves passing therethrough at a predetermined point beyond the limits of the conductor, and this conductor may vary widely in shape or form, the shape or form depending upon the relative position of the source of sound, and the predetermined point at which it is to be concentrated. In the best constructions, and as shown, this conductor, marked 1, is circular in cross section, and of varying diameter. The conductor 1 is paraboloidal in shape, its walls being formed to cause concentration of the sound-waves at a predetermined point 011 the axial line of the conductor.

In the device illustrated, S indicates the source of sound and the broken lines within the conductor indicate a number of sound wave increments and their course therethrough, the point of concentration being marked C. It is obvious that the conditions may be reversed and sound transmitted from C to and concentrated at S. It is obvious also that the sound-waves in passing through the conductor will not cross its axial line and that, therefore, there will be no sound crashes produced which detract from the initial purity of the sound. The inner wall of the conductor, marked 2, is, in the best constructions, formed of a hard deflecting material. Any suitable material such as metal or glass may be used for this purpose.

lVhen it is desired to prevent the propagation of secondary sound-waves from the outside of the conductor, the wall of the same is, in the best constructions, backed by sound absorbing material which may vary widely in character. Velvet or plush has been found suitable for this purpose. By the use of material of this nature the secondary sound-waves which are produced by the hard deflecting walls of the couihu-tm', are absorbed within the body of the backing, and no secondary sound-waves are propagated in the air.

\Vhen the source of sound and point of concentration occupy the relative positions indicated in the device illustrated, the conductor will progressively increase in diameter toward the center, as is clearly shown in the drawing.

Changes and variations may be made in the device by which the invention is carried into etlect. The invention is not, therefore,

to be restricted to the precise details of construction illustrated and described.

lVhat is claimed is:

1. A hollow conductor for sound recording and reproducing machines, the wall of which is formed of a hard deflecting material backed by sound absorbing material and shaped to cause concentration of sound waves passing therethnmgh at a predeter mined point, substantially as described.

2. A. hollow paraboloidal conductor for sound recording and reproducing machines, the wall of which is "formed. of a hard deflecting material backed by a sound absorl ing material and shaped to cause concentration of sound waves passing therethrough at a predetermined point beyond the limits of the conductor, substantially as described.

A hollow conductor tor sound recording and reproducing machines the outer wall of which is formed of a sound absorbing ma terial, substantially as described.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

SYDNEY I. PRESCOTT.

Witnesses:

FRANK B. Minnmrrolv, Jr, E'rnnL M. urrnnnrn. 

